oe The Philippine Journal of Science 1920 
in amounts sufficient to prevent or even check growth. Further 
work is now being carried on upon this subject. 
DISCUSSION OF RESULTS 
A 1 to 100 solution of phenol, in the absence of organic sub- 
stances, is entirely effective against Pseudomonas citri at an 
exposure of 24 minutes. Mercuric bichloride at a dilution of 1 
to 20,000 under the same conditions is also effective against 
P. citri at an exposure of 24 minutes; Liquor cresolis compositus, 
at an exposure of the same length, will kill in a 1 to 300 solution; 
formalin, to kill under the same conditions, requires a 1 to 20 
solution; an emulsion composed of Liquor cresolis compositus 
and kerosene is safely effective in a 1 to 50 dilution. Of the com- 
mercially used fungicides lime sulphur is effective at a dilution 
of 1 to 1,000 for an exposure of 24 minutes; copper sulphate is 
a safe bactericide only at a dilution of 1 to 200 for the same 
length of exposure; neutral Bordeaux mixture has no bacteri- 
cidal effect whatsoever even at exposures of 30 and 60 minutes; 
Bordeaux 4—4—50 mixture, undiluted, is not a safe bactericide 
against P, citri at an exposure of 24 minutes, but at 15 minutes’ 
exposure it was effective against P. citri in nearly all of the 
tests; Bordeaux mixture 4—6-50, a mixture in which the lime 
was considerably in excess, showed toxic action in 24 minutes 
when diluted with 4 parts of water; unslaked lime (commercial) 
at a dilution of 1 to 1,000 was effective against P. citri for the 
same length of exposure. Burgundy mixture 3~3-50 was en- 
tirely effective against P. citri, and Burgundy 3-4-50 mixture 
showed toxic action only at the longer exposures, even when un- 
diluted. 
The application of these results in the orchard should be 
somewhat as follows: For disinfection of clothing, implements, 
etc., in canker-eradication work, mercuric bichloride as used, at a 
dilution of 1 to 2,000, is the most effective and, probably, under 
most conditions is the cheapest. In eradication work the occa- 
sion sometimes arises where, an infected tree being found and 
burned, it is desirable to spray the surrounding trees to kill 
any of the canker organisms which may exist on the surfaces of 
their foliage. In such cases formalin 1 to 100 has frequently 
been used in the past. The use of formalin 1 to 100 was rec- 
ommended by Kellerman * in the Yearbook of the United States 
Department of Agriculture. According to these tests formalin 
* Kellerman, K. F., Cooperative work for eradicating citrus canker, Year- 
book U. S. Dept. Agr. for 1916 (1917) 270. 
